Anisotropy effects in thick layered CuInP2S6and CuInP2Se6crystals

Results of broadband dielectric investigations of thick layered CuInP2S6 and CuInP2Se6 crystals in direction parallel and perpendicular to the layers are reported. No dielectric anomaly indicates spontaneous polarization appearance in the direction parallel to the layers in CuInP2S6 and CuInP2Se6 crystals. In this direction the dielectric dispersion is mostly caused by Maxwell-Wagner relaxation and ionic conductivity. The typical for ferroelectric phase transition dielectric anomaly is observed only in the direction perpendicular to the layers in both crystals. The activation energy of DC conductivity is much higher in the direction perpendicular to the layers, which confirms ionic nature of electrical conductivity in both crystals.